Water bottles and containers for water coolers generally contain between about 3-7 gallons of fluid—typically about 4 or 5 gallons of filtered or purified water. The water bottles are normally installed on the water cooler in an inverted position, with the neck of the water bottle being received by a mating receptacle of the water cooler and the neck generally supporting a majority of the weight of the water bottle. In order to dispense water from the water cooler, a standard button or handle of the water cooler is depressed or otherwise actuated in a conventional manner, which opens a conventional flow valve allowing the water, contained within an internal cavity of the water bottle, to flow out of the internal cavity due to gravity. With the valve open, the weight of the column of water in the water bottle forces the water out through the opening in the neck of the water bottle and into the water cooler for dispensing to the consumer. As the water flows out of the internal cavity of the water bottle, such flow gradually reduces the total volume of the water contained within in the water bottle, and thereby normally creates a vacuum within the internal cavity the water bottle.
As water continues to be dispersed from the water bottle, the internal vacuum of the internal cavity continues to increase up into the point that either a replacement volume of air is permitted to enter into the internal cavity of the water bottle to relieve the created vacuum, or the side wall of the water bottle eventually commences collapsing radially inwardly, or possibly both events occur at about the same time. The created internal vacuum and the associated inwardly pushing force of the atmospheric pressure on the lateral walls of a water bottle can compromise the structural integrity of the water bottle, causing the side wall of the water bottle to bend, crimp and/or crumple inward, and potentially causing a leak or a fracture in the exterior surface of the water bottle or possibly causing the water bottle to become dislodged with the water cooler.
It is to be appreciated that water bottles with a circular transverse cross-section are generally more robust in withstanding the higher internal vacuums created within their internal cavity, as their circular side wall has a tendency of dissipating and/or dispersing this negative pressure more evenly throughout the circular sidewall. However, water bottles or containers having a circular cross section are less efficient for both package as well as shipping, in comparison to water bottles which have a generally square or rectangular transverse cross section.
Additionally, when packing and shipping filled water bottles, the water bottles must have sufficient top load strength in order to permit stacking of pallets of the water bottles, one on top of the other, in order to minimize the associated shipping costs. That is, filled water bottles are typically loaded on a pallet and then the pallets containing the plurality of water bottles are stacked either two or three pallets high, e.g., either one or two additional pallets are stacked on top of the base pallet containing a plurality of water bottles, during shipping from the bottling facilitate to the distributor or the end consumer. Such stacking of the pallets, one on top of the other, in combination with vertical undulations which normally occur during shipment and/or transportation, can create significant vertical compressive forces on the water bottles, and especially for the water bottles located on the base pallet of the stack of pallets. These vertical compressive forces can be sufficiently high so as to collapse the pallet and/or compromise the structural integrity of the water bottle, possibly causing one or more of the water bottles to bend, crimp and/or crumple inward or outward thereby causing a leak or a fracture in the wall of the water bottle(s) and/or significant distortion of the water bottle(s) thereby rendering the water bottle(s) potentially generally unfit for sale upon reaching the consumer.
Assuming the mass of the blow molded bottle is to remain the same, it is to be appreciated that typically any bottle design changes which improve lateral wall strength will typically weaken the top loading strength of the water bottle which makes the water bottle more susceptible to failure during transit. Conversely, any typical bottle design changes which improve the top loading strength of the water bottle will typically weaken the lateral wall strength of the water bottle, thereby making the water bottle more susceptible to failure as a result of the internal vacuum created when a consumer dispenses water from the water bottle using a conventional water cooler. Both of the above underscore the complexity in attempting to design a water bottle which addresses both of the above noted concerns, while still resulting in a water bottle which has both sufficient top load strength as well as lateral wall strength.
As is well known in the art, the incorporation of one or more horizontal annular ribs and other annular features will typically improve the lateral wall strength of the container, while the incorporation of one or more vertically extending ribs, columns or other vertical features will generally improve the top load strength of the container.